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Biomedical subjects

J McInerney

Publications and source records attributed to J McInerney.

18 recordsLinked to original sources
PubMed2001

Decision analysis for small, asymptomatic intracranial arteriovenous malformations.

OBJECT: Asymptomatic intracranial arteriovenous malformations (AVMs) represent a clinically challenging problem because of the complex decision making that must be undertaken prior to beginning any type of treatment. In addition, the relative infrequency of these lesions means that there is relatively little experience reported in the literature. The authors use a decision-analysis technique to model the considerations that go into determining the treatment of these lesions in an effort to quantify the various risks and overall benefits conferred by the following three treatment strategies: observation/natural history, microsurgery, and stereotactic radiosurgery. METHODS: The authors conducted a thorough literature search to elucidate the risks and outcomes associated with each treatment option. These values were used to build and run a comprehensive Markov model to determine a base-case analysis. All of the input variables were also subjected to sensitivity analysis to identify the most influential input variables and the crossover points in which favored strategies changed. The base-case analysis suggested that microsurgery was the favored treatment option because this hypothetical cohort accumulated 21.53 quality-adjusted life years (QALYs) over the course of the model compared with the 16.97 QALYs and 16.40 QALYs for stereotctic radiosurgery and observation, respectively. Sensitivity analysis demonstrated that overall major neurological morbidity and mortality were the most influential input variables both perioperatively and during the radiosurgical "latent" period (that is, up to 2 years posttreatment). The maximum acceptable perioperative combined major neurological morbidity and mortality rate was 6.8%. The latent period combined major neurological morbidity and mortality would need to be 0.7% to make radiosurgery favorable in this analysis. CONCLUSIONS: Results of this decision analysis model suggest that microsurgery in the hands of experienced cerebrovascular surgeons, who can expect a less than 6.8% combined rate of major neurological morbidity and mortality, offers patients a greater overall quality of life over time.

Algorithms↗
PubMed2000

Molecular cloning of an Atlantic salmon nucleoside diphosphate kinase cDNA and its pattern of expression during embryogenesis.

To gain insight into the process of development in Atlantic salmon (Salmo salar), we sought to identify genes that were differentially expressed at gastrulation. A polymerase chain reaction-based differential screening strategy allowed for the isolation of an Atlantic salmon nucleoside diphosphate kinase cDNA (nm23). Structural characterisation showed a high degree of homology with a large number of previously isolated nucleoside diphosphate kinases (NM23s), both prokaryote and eukaryote, though it represents the first teleost nucleoside diphosphate kinase identified. Highest similarities were found with the type 1 and type 2 NM23 isoforms of mammals. Phylogenetic analysis indicates that the duplication event that gave rise to these isoforms occurred after the splitting of tetrapods and fish, suggesting that the salmon NM23 represents a more ancestral isoform. The position of the salmon sequence on the phylogenetic tree indicates that the salmon genome is expected to have at least three copies of genes from the nm23 gene family. Northern blot analysis showed a single transcript of approximately 0.7 kb in both embryonic and adult tissues. Examination of the temporal pattern of expression of salmon nucleoside diphosphate kinase during embryonic development revealed that this gene is first expressed at the time of gastrulation. Nucleoside diphosphate kinases are thought to have a vital role in regulatory processes such as signal transduction, proliferation and differentiation. Taken together, these results suggest that nucleoside diphosphate kinases have an important role to play in early embryogenic development in vertebrates.

Amino Acid Sequence↗
PubMed2000

The pathophysiology of thoracic disc disease.

Nucleus pulposus herniations are far less common in the thoracic spine than at the cervical and lumbar regions. Traditionally, diagnosis of thoracic disc herniations has been challenging because the signs and symptoms are often subtle early in their course. As a result, delays in diagnoses are common. Because they are uncommon as well as difficult to diagnosis, the neurosurgical community has sparse data on which to base good clinical decision making for the treatment of these herniations. In this review the authors seek to place the phenomenon of thoracic disc disease into the context of its pathophysiology. After a careful evaluation of the available clinical, pathological, and basic science data, a case is made that the cause of nucleus pulposus herniations in the thoracic spine is similar to those occurring in the lumbar and cervical regions. The lower incidence of herniations is ascribed primarily to the reduced allowable flexion at the thoracic level compared with the lumbar and cervical levels. To a lesser extent, the contribution of the ribs to weight-bearing may also play a role. Further review of clinical data suggests that thoracic disc herniations, like herniated cervical and lumbar discs, may be asymptomatic and may respond to conservative therapy. Similarly, good surgery-related results have been reported for herniated thoracic discs, despite the more challenging nature of the surgical procedure. The authors conclude that treatment strategies for thoracic disc herniations may logically and appropriately follow those commonly used for the cervical and lumbar levels.

Back Pain↗
PubMed2000

The role of intracranial electrode reevaluation in epilepsy patients after failed initial invasive monitoring.

PURPOSE: Intracranial electrode recording often provides localization of the site of seizure onset to allow epilepsy surgery. In patients whose invasive evaluation fails to localize seizure origin, the utility of further invasive monitoring is unknown. This study was undertaken to explore the hypothesis that a second intracranial investigation is selected patients warrants consideration and can lead to successful epilepsy surgery. METHODS: A series of 110 consecutive patients with partial epilepsy who had undergone intracranial electrode evaluation (by subdural strip, subdural grid, and/or depth electrodes) between February 1992 and October 1998 was retrospectively analyzed. Of these, failed localization of seizure origin was thought to be due to sampling error in 13 patients. Nine of these 13 patients underwent a second intracranial investigation. RESULTS: Reevaluation with intracranial electrodes resulted in satisfactory seizure-onset localization in seven of nine patients, and these seven had epilepsy surgery. Three frontal, two temporal, and one occipital resection as well as one multiple subpial transection were performed. Six patients have become seizure free, and one was not significantly improved. The mean follow-up is 2.8 years. There was no permanent morbidity. CONCLUSIONS: In selected patients in whom invasive monitoring fails to identify the site of seizure origin, reinvestigation with intracranial electrodes can achieve localization of the region of seizure onset and allow successful surgical treatment.

Adolescent↗
PubMed2000

Frameless stereotaxy of the brain.

Today's neurosurgical journals are replete with advertisements for systems designed to provide image guidance during surgery. These so-called "frameless" stereotactic systems provide the surgeon with navigational information, relating the location of instruments in the operative field to preoperative imaging data. Such information minimizes invasiveness by more accurately selecting the best trajectory to the lesion, ensures more precise identification of normal structures, and guides complete removal of a lesion. To achieve these goals, all of these systems utilize the stereotactic principle of co-registration of the patient with an imaging study. This review will trace the development of image-guided surgery from its origins in frame-based stereotaxy to its current use as a surgical navigation methodology. A review of the more prevalent techniques and available systems will be presented, along with examples of specific applications of surgical navigation. Finally, some of the future directions of frameless stereotaxy will be discussed.

Brain↗
PubMed1999

Targeted remodeling of human beta-globin promoter chromatin structure produces increased expression and decreased silencing.

The chromatin structure of the human beta-globin gene locus assumes a transcriptionally-active conformation in erythroid cells. One feature of this chromatin reorganization is the formation of DNase 1 hypersensitive sites in the regions of active globin gene promoters. This reorganization requires the globin locus control region and is associated with normal expression of the beta-like globin genes. To determine whether it is possible to artificially enhance the opening of the chromatin structure of a minimal beta-globin promoter, we placed a 101bp, erythroid-specific DNase 1 hypersensitive site-forming element (HSFE) immediately upstream of the beta-globin promoter and gene. This element includes binding sites for NF-E2, AP-1, GATA-1 and Sp-1. Constructs were stably transfected into murine erythroleukemia cells and promoter chromatin structure and gene expression were analyzed. The HSFE induced an area of enhanced DNase 1 hypersensitivity extending from the transcriptional start site to -300bp of the artificial promoter and significantly increased the proportion of beta-globin promoters in an open chromatin configuration. This remodeling of promoter chromatin structure resulted in 3-fold increases in beta-globin gene transcription and induction, and inhibited long-term beta-globin gene silencing. These results indicate that a relatively small cis-acting element is able to enhance remodeling of promoter chromatin structure resulting in increased beta-globin gene expression.

Chromatin↗
PubMed1999

Long-term seizure outcome following corpus callosotomy in children.

INTRODUCTION: The long-term outcome of pediatric patients undergoing corpus callosotomy (CC) for palliative control of medically intractable seizures is presented. METHODS: During a 27-year period, 43 patients, 20 years of age or younger, underwent CC for seizure palliation and had a minimum of 1 year follow-up. Seizure reduction and stability of that outcome for individual seizure types and for most disabling seizure were reviewed. RESULTS: Overall, 63% of the seizures documented showed a good response. For the most disabling seizure, 56% of the patients had good outcomes. Changes in outcome status occurred within the first 6 months, and outcome was largely maintained after that point. CONCLUSION: Callosotomy achieves the goal of seizure palliation in more than half of the patients, with stable, good outcomes being maintained in the majority of patients.

Adolescent↗
PubMed1999

Coregistered ultrasound as a neurosurgical guide.

INTRODUCTION: The dynamic nature and three dimensionality of ultrasound data can be utilized to enhance the capabilities of image guidance systems. METHODS: Coregistration of ultrasound data was done using an electromagnetic digitizer, and subsequent ultrasound images were correlated with preoperative MRI studies. Thirty-two patients undergoing craniotomy were investigated in this manner. RESULTS: Phantom testing done with a rigid stylus and 3D ultrasound tracker demonstrated an accuracy of 1.36 +/- 1.67 mm in determining the location of a point. Thirty-two clinical cases were coregistered without difficulty. CONCLUSION: Coregistered ultrasound is a useful methodology that can aid in neuronavigation.

Brain↗
PubMed1997

Economic analysis of alternative AD control programmes.

The threat imposed by its virulence brings a presumption that Aujeszky's disease (AD) must be controlled because potential losses are high. Viewed as an economic problem, the decision on whether and how to control AD hinges on comparing the costs of doing so with the benefits (in terms of reduced production losses) to be gained. Four strategies are considered: (a) doing nothing, (b) suppressing and maintaining the disease at low prevalence levels by vaccination, (c) suppressing to low levels and then eradicating by culling remaining positive animals and (d) eradicating in one step by means of a test-and-slaughter policy. The net economic merits of each strategy are examined using data derived from specific vaccination studies established in Germany and the Netherlands. A computer model is developed to estimate disease costs under different technical, epidemiological and economic assumptions, allowing the economically optimal strategies to be explored. In general no single strategy can be recommended as the 'best' for dealing with AD, since it depends on a host of factors relating to pig density, prevalence levels, production system, trade relations, etc. As usual, economic realities complicate the quest for operational simplicity in disease control. However, for the regions of high pig density studied the most economic AD control strategy is to lower herd prevalence by intensive vaccination before completing eradication by test-and-removal of remaining positive animals.

Animals↗
PubMed1996

Scombroid poisoning.

Scombroid poisoning is described in the literature as a toxic poisoning caused by ingestion of certain dark meat fish undergoing bacterial decomposition. Poisoning results from the ingestion of a heat-stable toxin. We describe the case of a man who presented to the emergency department several hours after eating tuna steak with evidence of scombroid poisoning that was associated with loss of vision and atrial tachycardia with block. All signs and symptoms resolved after treatment for scombroid poisoning.

Acute Disease↗
PubMed1995

Prevalence of Mycobacterium bovis infection in feral pigs in the Northern Territory.

The prevalence of Mycobacterium bovis infection in populations of feral pigs from five areas in the Northern Territory was examined. In total 790 pigs were necropsied and positive cultures of M bovis were obtained from two pigs (0.25%) and a mycobacterial granuloma was found in one pig. The observed prevalence of M bovis infection in feral pigs is significantly less (chi 2 = 139.8, df = 1, P < 0.001) than the results of a comparable survey conducted during the early 1970s before the implementation of the Brucellosis and Tuberculosis Eradication Campaign. The prevalence of all types of macroscopic lesions resembling tuberculosis was significantly (chi 2 = 338.7, df = 1, P < 0.001) less than the earlier survey. The results are further support for the hypothesis that in the Northern Territory feral pigs are an end-host for M bovis infection, and that the previous high prevalence of M bovis recorded in feral pigs in the 1970s was caused by the close association between these animals and large populations of M bovis-infected buffalo and cattle.

Aging↗
PubMed1990

An associative process maintains reflex facilitation of the unconditioned nictitating membrane response during the early stages of training.

The presentation of a neutral or conditioned stimulus (CS) at an appropriate interval prior to the presentation of a corneal airpuff, or a paraorbital shock (unconditioned stimulus, US) can facilitate the amplitude of the unconditioned nictitating membrane (NM) response in rabbit. In two experiments, it was demonstrated that an associative process mediates the maintenance of that facilitation during repeated CS-US pairings. Although CS-alone presentations produced a substantial decrease in the amount of reflex facilitation in animals not pretrained with the CS, pretraining that consisted of paired CS-US presentations prevented that decrease when CS-alone presentations were subsequently given. Conditioned facilitation of the unconditioned response occurred very rapidly (within 5-12 trials in these experiments) and long before the appearance of overt conditioned responses to the CS. In addition, it was demonstrated that conditioned facilitation can be relatively specific to the tonal frequency of the CS. These results indicate the first sign of conditioning of the NM response is exhibited in the amplitude of the unconditioned response.

Animals↗